Fluid product dispensing pump

ABSTRACT

A fluid dispenser pump comprising a pump body ( 10 ) containing a pump chamber ( 11 ) defined between an upper piston ( 20 ) and a lower piston ( 30 ), said pistons ( 20, 30 ) being mounted to slide in leaktight manner in said pump body ( 10 ), said pump chamber ( 11 ) being provided with an inlet valve ( 40 ) and with an outlet valve ( 50 ), said lower piston ( 30 ) co-operating with said outlet valve ( 50 ), when the full dose has been metered out, to open said outlet valve and to make it possible to deliver the fluid contained in the pump chamber ( 11 ), said dispenser pump being characterized in that the lower piston ( 30 ) is separate from the inlet valve seat ( 42 ) and is mounted to float in the pump chamber ( 11 ), said lower piston ( 30 ) being returned to its rest position by said inlet valve seat ( 42 ).

[0001] The present invention relates to a fluid dispenser pump.

[0002] Fluid dispenser pumps are well known from the state of the art.Such a pump generally comprises a pump body which defines a pump chamberdisposed between an inlet valve and an outlet valve, with a pistonsliding in said pump body to deliver fluid contained in said pumpchamber. In certain cases, the pump can have two pistons, namely anupper piston and a lower piston, which pistons slide together in thepump body while it is being actuated, until the outlet valve opens andthe fluid contained in the pump chamber is delivered.

[0003] In certain cases, in particular with pharmaceuticals,dose-metering accuracy and guaranteed dispensing of a full dose eachtime the pump is actuated can be essential criteria. In particular, itis important to prevent incomplete doses from being dispensed, and toprevent the pump chamber from being filled in part only after said pumphas been actuated.

[0004] An object of the present invention is to provide a fluiddispenser pump that guarantees dose-metering accuracy each time the pumpis actuated, and that guarantees a full dose is dispensed.

[0005] Another object of the present invention is to provide such afluid dispensing pump that is simple and inexpensive to manufacture andto assemble.

[0006] To these ends, the present invention provides a fluid dispenserpump comprising a pump body containing a pump chamber defined between anupper piston and a lower piston, said pistons being mounted to slide inleaktight manner in said pump body, said pump chamber being providedwith an inlet valve and with an outlet valve, said lower pistonco-operating with said outlet valve, when a full dose has been meteredout, to open said outlet valve and to make it possible to deliver thefluid contained in the pump chamber, said dispenser pump beingcharacterized in that the lower piston is separate from the inlet valveseat and is mounted to float in the pump chamber, said lower pistonbeing returned to its rest position by said inlet valve seat.

[0007] Advantageously, the outlet valve comprises a valve member whichis mounted to move in the pump chamber and which is urged into itsclosure position by pressure from the fluid contained in the pumpchamber, said moving valve member being provided with a shoulder which,when a full dose has been metered out, co-operates with said lowerpiston or with an element integral therewith, so that the lower pistonlifts the valve member off its valve seat so as to open the outletvalve.

[0008] Advantageously, the outside diameter of the upper piston islarger than the outside diameter of the lower piston.

[0009] Advantageously, the valve seat of the inlet valve is urged by aresilient element such as a spring into the rest position of the pump,in which position said lower piston or an element integral therewithurges the outlet valve into its closure position.

[0010] Advantageously, the lower piston acts as a primer element forremoving the air contained in the pump chamber when the pump is actuatedfor the first time.

[0011] Advantageously, when the pump chamber contains air, an airremoval passageway is formed between the lower piston, the upper pistonand the inlet valve seat so as to enable the air to be removed from thepump chamber, said lower piston closing off said air passageway inleaktight manner when the pump chamber contains fluid to be dispensed.

[0012] Advantageously, the outlet valve member is provided with a secondshoulder which co-operates with said lower piston or with an elementintegral with said lower piston, when the pump is in the rest position,so that the lower piston urges said moving valve member into its closureposition.

[0013] Other characteristics and advantages of the present inventionwill appear more clearly on reading the following detailed descriptiongiven with reference to the accompanying drawings which are given by wayof non-limiting example and in which:

[0014]FIG. 1 is a diagrammatic section view of a pump of an advantageousembodiment of the present invention, in the rest position;

[0015]FIG. 2 is a view similar to the view in FIG. 1, in the primingposition; and

[0016]FIG. 3 is a view similar to the view in FIGS. 1 and 2, just beforethe fluid contained in the pump chamber is delivered.

[0017] With reference to the figures, the pump comprises a pump body 10in which an upper piston 20 and a lower piston 30 are mounted to slidein leaktight manner. Between said pistons 20 and 30 a pump chamber 11 isdefined that is provided with an inlet valve 40 and with an outlet valve50. The inlet valve 40 may be a ball valve comprising a ball 41co-operating with a corresponding valve seat 42. When the user actuatesthe pump, the two pistons 20 and 30 slide inside the pump body whileclosing the inlet valve 40 until the outlet valve 50 opens to enable thefluid to be delivered.

[0018] In the invention, the lower piston 30, or an element 70 integraltherewith, co-operates with the outlet valve 50 to open it when a fulldose has been metered out. A dose might not be metered out in full untilthe end of the actuating stroke of the lower piston 30, but it is alsopossible for a full dose to be metered out before said end of theactuating stroke. In which case, the outlet valve 50 opens before thelower piston has traveled over its full stroke. In particular, in theexample shown in the figures, the outlet valve 50 includes a movingoutlet valve member 51 which is mounted to move axially inside the pumpchamber 11, said moving valve member 51 being urged into its closedposition, in which it presses against its valve seat 52, by the pressurefrom the fluid disposed inside the pump chamber 11. This implementationguarantees excellent leaktightness at the outlet valve, because it isimpossible for said outlet valve to open in undesired manner before thefluid is delivered. Said valve member 51 is advantageously provided witha first shoulder 55 which co-operates with the lower piston 30 or withan element 70 integral with said lower piston 30, when the full dose hasbeen metered out, so that the lower piston 30 mechanically lifts thevalve member 51 off its valve seat 52 so as to open the outlet valve 50.Advantageously, the moving valve member 51 of the outlet valve 50 isalso provided with a second shoulder 56 which co-operates with the lowerpiston 30 or with an element 70 integral therewith, when the pump is inthe rest position, so that the moving valve member 51 is urged towardsit closed position.

[0019] Operation of the pump is described below with reference to FIGS.1 and 3.

[0020] In FIG. 1, the pump is in the rest position. When the useractuates the pump, said user exerts axial pressure on the upper piston20 which then slides inside the pump body 10. Since the fluid containedin the pump chamber 11 is incompressible, said fluid also causes thelower piston 30 to slide in leaktight manner inside the pump body 10.The inlet valve 40 is urged into its closed position by the pressurefrom the fluid inside the pump chamber, and the same applies for theoutlet valve 50, whose moving valve member 51 is also urged into itsclosed position by the pressure from the fluid inside the pump chamber11.

[0021] When a full dose has been metered out, the position shown in FIG.3 is reached. Since the diameter of the lower piston 30 is smaller thanthe diameter of the upper piston 20, the lower piston 30 or the elementthat is integral with the lower piston 30 and that is referenced 70 inthe figures, moves faster than the upper piston 20 while the pump isbeing actuated. It thus goes from its position in which it is in contactwith the second shoulder 56, as shown in FIG. 1, to its position inwhich it comes into contact with the first shoulder 55 of the movingvalve member 51. Whereupon the lower piston co-operates with the movingvalve member 51 to move it axially inside the pump chamber, by liftingit off its valve seat 52, in order to open the outlet valve 50 andthereby enable the fluid contained in the pump chamber 11 to bedelivered. The gap between the shoulders 55 and 56 determines the timeof opening of the outlet valve, and thus the volume of the dose to bedispensed. It is necessary merely to modify said gap in order to causethe volume of the dose to vary. The present invention thus makes it verysimple and very inexpensive to vary the volume of the dose to bedispensed, merely by modifying a single part of the pump.

[0022] As shown in the figures, the inlet valve 40 of the pump chamber11 includes a valve seat 42 floatingly mounted inside the pump body 10and urged by a spring into its rest position shown in FIG. 1. The spring60 is the return spring of the pump. Advantageously, the lower piston 30is provided with a shoulder which cooperates with said seat of the inletvalve 42 so that, when the outlet valve is opened, the fluid containedin the pump chamber 11 is delivered by means of said lower piston 30,which is returned into its starting position by the spring 60 which actson the valve seat 42.

[0023] In the invention, the lower piston 30 is made separately from theinlet valve seat 42. The advantage of making the lower piston 30separately is described below with reference to FIG. 2 and in relationto a particular embodiment of the invention.

[0024] When the outlet valve 50 is opened, the fluid contained in thepump chamber 11 is thus delivered from said pump chamber, the lowerpiston rising inside the pump body 10 under drive from the compressedspring 60 until the lower piston 30, or the piece 70 integral with saidlower piston 30, comes into abutment again against the second shoulder56 of the moving valve member 51 of the outlet valve 50 so as to urgesaid valve member into its closed position. The suction generated in thepump chamber by the fluid being delivered and by the pistons risingopens the inlet valve 40, said ball thus being lifted off its valve seatto enable a new dose of fluid to be sucked into the pump chamber 11.

[0025] The invention thus offers two essential advantages. Firstly itguarantees that a dose is delivered in full each time the pump isactuated, by preventing any partial dispensing of the contents of thepump chamber 11. The outlet valve 50 cannot open until a full dose hasbeen metered out, regardless of the actuating force exerted by the useron the pump. Secondly, the accuracy of dose-metering is guaranteed bythe outlet valve closing automatically after the dose has beendelivered.

[0026] In the invention, the lower piston 30 is made separately from theinlet valve seat 42. By making the lower piston 30 separately from theinlet valve seat 42, and by mounting said lower piston 30 to floatinside the pump body, it is possible to use said lower piston as aprimer element. As shown in FIG. 2, the first time the pump is actuated,when the pump chamber 11 contains air, the lower piston 30 lifts offfrom the inlet valve seat 42, because air is compressible, and itgenerates a passageway through which air can flow out between the lowerpiston 30 and said inlet valve seat 42, thereby enabling the aircontained in the pump chamber 11 to be removed. Air also flows outthrough a passageway between the lower piston 30 and the upper piston 20via one or more grooves 29 provided in an end surface of the upperpiston 20, and which co-operate(s) with the lower piston 30 at the endof the stroke traveled when the pump is actuated for the first time, asshown in FIG. 2. The groove 29 thus co-operates with the lower piston 30in a position which makes it possible to limit the dead volume of thepump chamber 11 so that almost all of the air contained in said pumpchamber is removed in the position shown in FIG. 2. When the user ceasesto press on the pump starting from the position shown in FIG. 2, theentire mechanism of the pump rises under drive from the return spring60, so that the pump chamber fills with fluid via its inlet valve 40. Assoon as the fluid enters the pump chamber 11, said lower piston 30 isurged automatically by the fluid into its position shown in FIGS. 1 and3, in which position the lower piston 30 co-operates with the valve seat42 so as to close off said above-mentioned passageway through which aircan flow out. Whereupon, said lower piston 30 can no longer lift offfrom the valve seat 42 because of the presence of incompressible fluidinside the pump chamber 11. When the pump is actuated on subsequentoccasions, the lower piston 30 and the valve seat 42 then act as aone-piece unit, providing excellent leaktightness, and preventing anyfluid from leaking out through the air removal passageway that serves toprime the pump. Naturally, the embodiment shown in the figures is anadvantageous particular embodiment, but it is quite possible to considerproviding other primer means for priming the pump, without necessarilyusing the lower piston for this purpose.

[0027] Other modifications may be made by the person skilled in the artwithout going beyond the ambit of the present invention, as defined bythe accompanying claims.

1/ A fluid dispenser pump comprising a pump body (10) containing a pumpchamber (11) defined between an upper piston (20) and a lower piston(30), said pistons (20, 30) being mounted to slide in leaktight mannerin said pump body (10), said pump chamber (11) being provided with aninlet valve (40) and with an outlet valve (50), said lower piston (30)co-operating with said outlet valve (50), when the full dose has beenmetered out, to open said outlet valve and to make it possible todeliver the fluid contained in the pump chamber (11), said dispenserpump being characterized in that the lower piston (30) is separate fromthe inlet valve seat (42) and is mounted to float in the pump chamber(11), said lower piston (30) being returned to its rest position by saidinlet valve seat (42). 2/ A pump according to claim 1, in which theoutlet valve (50) comprises a valve member (51) which is mounted to movein the pump chamber (11) and which is urged into its closure position bypressure from the fluid contained in the pump chamber (11), said movingvalve member (51) being provided with a shoulder (55) which, when a fulldose has been metered out, co-operates with said lower piston (30) orwith an element (70) integral therewith, so that the lower piston (30)lifts the valve member (51) off its valve seat (52) so as to open theoutlet valve (50). 3/ A pump according to claim 1 or claim 2, in whichthe outside diameter of the upper piston (20) is larger than the outsidediameter of the lower piston (30). 4/ A pump according to any precedingclaim, in which the valve seat (42) of the inlet valve (40) is urged bya resilient element (60) such as a spring into the rest position of thepump, in which position said lower piston (30) or an element (70)integral therewith urges the outlet valve (50) into its closureposition. 5/ A pump according to any preceding claim, in which saidlower piston (30) acts as a primer element for removing the aircontained in the pump chamber (11) when the pump is actuated for thefirst time. 6/ A pump according to claim 5, in which, when the pumpchamber (11) contains air, an air removal passageway is formed betweenthe lower piston (30), the upper piston (20) and the inlet valve seat(42) so as to enable the air to be removed from the pump chamber (11),said lower piston (30) closing off said air passageway in leaktightmanner when the pump chamber (11) contains fluid to be dispensed. 7/ Apump according to any preceding claim, in which the outlet valve member(51) is provided with a second shoulder (56) which co-operates with saidlower piston (30) or with an element (70) integral with said lowerpiston (30), when the pump is in the rest position, so that the lowerpiston (30) urges said moving valve member (51) into its closureposition.